Over the past several years, the use of magnetic media has increased greatly. Magnetic storage technology provides an inexpensive and fairly reliable high density media for storage of all types of data associated with personal computers. For example, electronic versions of images, documents, facsimiles, etc. may all be stored conveniently and compactly on magnetic media.
Typically, a circular thin sheet of magnetic material is mounted on a central metal hub, and is encased within a plastic shell. The plastic shell has an upper and lower portion thereof which portions are bonded together to form the entire enclosure.
FIG. 1 shows a typical prior art magnetic disc as it is assembled. The arrangement of FIG. 1 includes an upper member 7, and a lower member 8, which are preferably made of plastic compounds. Two wiper elements, 11 and 12, are made of cloth in accordance with techniques known to those of ordinary skill in the art. The magnetic medium 1 is then sandwiched between wiper elements 11 and 12 by connection of the upper and lower members 7 and 8 respectively. A metal hub 2 is installed at the center of the disc to facilitate rotation, and a shutter 20 is mounted across the openings 14 and 17 of the upper and lower members 7 and 8 respectively, all in accordance with techniques well known to those of ordinary skill in this art.
A lifter tab 13 is mounted behind a rib 30 in order to assist the wiper elements 11 and 12 in cleaning the debris from magnetic medium 1. The lifter tab 13 is usually manufactured from a thin plastic material. The resiliency of the lifter tab tends to press cleaning element 12 against magnetic medium 1 in order to facilitate cleaning of magnetic medium 1.
FIG. 2 shows a side cross sectional view of the lifter tab 13 as installed in the completed disc. The rib 30 causes lifter tab 13 to be forced upwardly into contact with wiper element 12, which causes wiper element 12 to exert a small amount of pressure on magnetic medium 1. The pressure is sufficient to cause a sandwiching of magnetic medium 1 between wiper elements 11 and 12, thereby assisting the wiper elements in removing articles of debris from magnetic medium 1.
It is generally recognized in the industry that the lifter tab is required in order to prevent rapid degradation in the performance of magnetic media due to the build up of dust and dirt particles. First, the lifter tab itself constitutes an additional part which is subject to failure. Second, it increases the assembly time because it adds an additional step to the manufacturing process; namely, the mounting of the lifter tab. 0f course, this step must be accomplished at the proper location, orientation, etc., and also requires some type of glue or other adhesive.
Another prior art magnetic storage medium is disclosed in U.S. Pat. No. 4,626,949 to Brock. Brock, as best seen by FIG. 2 thereof, discloses the use of ribs which cause a bending of the magnetic medium. This reference explicitly teaches that the magnetic medium should be forced to bend in alternate directions (i.e.; up and down) as the medium rotates within the cartridge. (See FIG. 2 and associated text at col. 4, line 7-11, explaining the "bending about the projections") However, the bending creates increased wear and tear on the disc.
In view of the above problem, it can be appreciated that there exists an unsolved need in the prior art for a technique that allows proper debris removal from the magnetic medium, yet eliminates the complex manufacturing step of installing the lifter tab as well as the need for the lifter tab itself.